1. Field of Invention
The invention relates to systems and methods for controlling a self-reconfigurable robot.
2. Description of Related Art
Modular self-reconfigurable robots are a relatively new concept. A modular self-reconfigurable robot includes a plurality of identical modules that can attach and detach from one another to change the overall topology of the robot. Each module is a self-contained unit with its own processing, sensing and actuation systems. A modular self-reconfigurable robot can dynamically adapt its shape to suit the needs of the task at hand by manipulating the individual modules to individually move each module to a desired position. Such shapes are unlikely to be as effective for particular tasks as special purpose tools. However, a modular self-reconfigurable robot can respond to a wide range of tasks and unpredictable environments.
As indicated above, each module is identical. Thus, any individual module is no more critical than any other module. If any particular module breaks down, that module can easily be replaced by another module. Furthermore, because the modules are identical, manufacturing costs can be reduced through mass production.
However, modular, self-reconfigurable robots that are formed by a plurality of modules pose several interesting control challenges. Self-reconfiguration, or how to change shape automatically, is a new and thus little-researched problem. Decentralized control is a useful approach to this problem due to the large number of modules in a typical modular, self-reconfigurable robot and because each module is a self-contained unit with its own processing, sensing and actuation. Thus, distributed multi-agent control is particularly relevant.
The problem of self-reconfiguration is unique to metamorphic robots, i.e., robots which can change their shape according to a particular task. Ideally, reconfiguration should occur in a minimum number of steps to reduce the time for reconfiguration and to simplify the structure. Such an optimal solution to reconfiguration involves searching the space of all possible reconfiguration sequences for the optimal reconfiguration sequence. The amount of robot reconfigurations varies according to all of the possible arrangements for a set of connected modules, which grows exponentially with the number of modules. Therefore, for modular, self-reconfigurable robots with hundreds of modules or more, the number of possible reconfigurations thus increases the difficulty in finding the optimal solution.
A number of algorithms can be used to find near-optimal solutions for different modular, self-reconfigurable robot systems. These methods require determining and defining, before reconfiguration, a precise specification of the desired location of all the modules, a desired shape, and an identification of all the motions for the modules according to some criteria, such as minimizing the number of moves or the power consumption. However, in many practical applications, defining an exact target shape may not be suitable or even possible. Thus, such algorithms cannot be used when the nature of the environment or task is uncertain, for example, when grasping an object of unknown size or shape.
The invention provides a self-reconfigurable robot with a plurality of modules used to create a structure required to achieve a task.
This invention separately provides a self-reconfigurable robot having a plurality of modules where control of the modules can be expressed largely in terms of the local environment.
This invention separately provides systems and method where, for each module, agent-based control is used to achieve a suitable shape without needing to precisely specify the exact position of each module.
This invention separately provides a self-reconfigurable robot where agent-based architectures are well suited for decomposing control problems based on different physical characteristics at different scales.
This invention separately provides a self-reconfigurable robot where any stable structure that exhibits the desired properties is satisfactory, with no regard for the optimality of the result or for the resulting geometry.
In various exemplary embodiments, the systems and methods according to this invention provides a self-reconfigurable robot which comprises a plurality of modules. Each module is cubic in shape with each of the faces including an arm for expansion and contraction with another module and for communication with the another module.
In various exemplary embodiments, to control the plurality of modules in creating a snake configuration, a module is randomly chosen to emit a first scent along an axis of configuration and a second scent in a direction perpendicular to the axis, wherein the modules along the axis remain along the axis and propagate the second scent in the direction perpendicular to the axis and the other modules are controlled by the second scent to move toward the axis.
In various exemplary embodiments, to control the plurality of modules in creating a support structure, when a module receives a force greater than a predetermined value, the module sends a first scent along an axis, a second scent in a perpendicular direction from the axis, and thereafter forms a rigid support. The other modules then form a rigid support upon receipt of the first scent and propagate the second scent in the direction perpendicular to the axis while modules in receipt of the second scent expand toward the second scent.
In various exemplary embodiments, to internally manipulate an object within a plurality of module, a module in the direction of movement moves toward the module and the modules not in the direction of movement are moved away from the object, wherein the modules are moved into contact with the object and away from the object until the object is at a final location.
These and other features and advantages of this invention are described and are apparent from the detailed description of various exemplary embodiments of the systems and methods according to this invention.